A gas turbine blade, which on the blade tip is equipped with a shroud segment, is known from EP-A1-1591 625. The shroud segments of the blades of a blade row together form an encompassing shroud. On the side edges, by which the adjacent shroud segments of a shroud abut, the shroud segments are provided with upwardly projecting side rails which extend along the side edges and improve the leak-proofness of the shroud in relation to the hot gas passage of the turbine. No statement is made about the cooling of the shroud segments or of the shroud.
A turbine blade arrangement, with a shroud in which the shroud segments are equipped with an encompassing sealing rib in which provision is made for a similarly encompassing slot, is known from DE-A1-196 01 818. An air flow which is fed there in the bottom region of the slot discharges on the upper edge of the sealing rib and in the gap between upper edge and adjoining passage wall intermixes with a leakage air flow. The air flow which is fed into the slot in this case can be obtained from a cooling air flow which is directed through the shroud segment. The main point for consideration in this case is still the reduction of leakage losses but not the cooling of the shroud segment.